An aerogel, as a high specific area (500 m2/g or more), ultra-porous material having a porosity of about 85% to 99.9% and a pore diameter of about 1 nm to about 100 nm, has excellent characteristics such as ultra lightweightness, ultra insulation, and ultra-low dielectric constant. Due to the excellent physical properties, research into the applications of the aerogel as a transparent insulator and an environmentally-friendly high-temperature insulator, an ultra-low dielectric thin film for a highly integrated device, a catalyst and a catalyst support, an electrode for a supercapacitor, and an electrode material for desalination as well as the development of an aerogel material has been actively conducted.
The biggest advantage of the aerogel is super-insulation having a thermal conductivity of 0.300 W/m·K or less which is lower than that of an organic insulation material such as a typical Styrofoam. Fire vulnerability and the generation of toxic gas in case of fire, i.e., fatal weaknesses of a typical organic insulation material, may be addressed due to the low thermal conductivity.
In general, a wet gel is prepared from a silica precursor such as water glass or tetraethoxysilane (TEOS), and an aerogel is then prepared by removing a liquid component in the wet gel without destroying its microstructure. The silica gel prepared by the above-described method is prepared in three forms, powder, granules, and monolith, and is mainly prepared in a powder form.
Silica aerogel powder may be normally commercialized in a form, such as an aerogel blanket or aerogel sheet, by compositing with fibers. Also, since the blanket or sheet, which is prepared by using a silica aerogel, has flexibility, it may be bent, folded, or cut to a predetermined size or shape. Thus, the silica aerogel may be used in household goods, such as jackets or shoes, as well as industrial applications such as an insulation panel of a liquefied natural gas (LNG) line, an industrial insulation material and a space suit, transportation and vehicles, and an insulation material for power generation. Furthermore, in a case where a silica aerogel is used in a fire door as well as a roof or floor in a home such as an apartment, it has a significant effect in preventing fire.
The core technology of aerogel manufacturing process is a drying technique capable of preparing a gel by drying without shrinkage while maintaining the structure of the wet gel. A typical drying method may include supercritical drying. However, production costs of the supercritical drying are not only high, but also there is a high risk due to the high pressure. Furthermore, since the supercritical drying is a process of using an autoclave in which a continuous process is not possible, the supercritical drying has many limitations in terms of economic factors, stability, and continuity of the process.